


Percussive Maintenance

by DexxxtroDNA



Category: Transformers: Prime
Genre: Canon Disabled Character, Consensual Sex, Discipline, Dom/sub Play, Light BDSM, M/M, Massage, Medical Examination, Orgasm Delay/Denial, Other, Predacons Rising spoilers, Season/Series 03 Spoilers, Seduction, Size Difference, Size Kink, Spanking, Spoilers, deadlock spoilers
Language: English
Status: Completed
Published: 2013-11-29
Updated: 2013-11-29
Packaged: 2018-01-02 22:20:18
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,619
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1062305
Author URL: https://archiveofourown.org/users/DexxxtroDNA/pseuds/DexxxtroDNA
Summary: <blockquote class="userstuff">
              <p>Ultra Magnus is having trouble adjusting to some of his combat injuries. Luckily for him, a certain sporty medic knows <i>exactly</i> the kind of help he needs.</p>
            </blockquote>





	Percussive Maintenance

**Author's Note:**

  * For [MlleMusketeer](https://archiveofourown.org/users/MlleMusketeer/gifts).



> SPOILERS FOR END OF SEASON 3 AND PREDACONS RISING
> 
> Prompt: "Fic. Knockout / Ultra Magnus. With sub!Ultra Magnus. Imagine Ultra Magnus's voice begging." - MlleMusketeer
> 
> Betaed by LeggyStarscream.
> 
> I can't help but mention my good friend and BDSM mentor Doc D. You're the most caring psycho doctor sadist I've ever met. <3

"You're just going to re-injure it if you don't learn how to _relax_ , you realize?" Knockout stepped up behind Ultra Magnus, who had been awkwardly trying to force his prosthetic hand open.

"I do not follow."

"If you stay so _tense_ all the time, you'll just put extra strain on the cabling and linkages. Stop forcing it, we need finesse here, not a warhammer." The medic's tone was harsh but his hands were skilled, and the pain from the locked up mechanisms dissipated.

"Don't think that fixed it. If you keep this up Ratchet's going to have to rebuild your forearm cabling and energon lines and we all know how _enjoyable_ those are. Really, I don't see how I'm always the one labelled the sadist, if you haven't seen the badly disguised glee on his face."

Ultra Magnus couldn't suppress a flinch.

"Indeed. Now, about keeping you out of Ratchet's domain? First thing is all these small, finely tuned parts are actually connected to linkages just below the elbow joint." Claw tipped fingers pressed at exactly the right angle to provide precise pressure without being on the sharp tips.

“But the _real_ problem is, unfortunately, quite out of my reach.” Knockout tapped one clawtip lightly as high up on Ultra Magnus’s shoulder as he could reach -- on tiptoe. Ultra Magnus obligingly sank to one knee, then the other.

A pointy pede kicked lightly between his own. “I can’t work on your shoulder cabling if I can’t stand where I need to, can I?”

“No, I suppose you cannot.” He spread his knees to create open space on the floor and felt Knockout step in behind him, the feel of his drawn in field only affording him superficial wavelengths.

Ultra Magnus felt the solid, sure touch of trained digits on his shoulder cabling, mapping out the scheme of wiring, tensile cables, hydraulics and energon lines. Then steady strokes loosened kinked up cables, small hands dug in and adjusted tension fittings.

“Ah, of course. Idler gear’s a mess - this wear pattern is so _typical_.”

“Of what?”

“Mechs like you, always holding yourself so stiffly. Exceeding your weight rating is easy when you attempt to carry a planet on your shoulders.” Knockout yanked sharply on a selector shaft. It hurt, but only from surprise, as Ultra Magnus felt a wave of release flow down his entire arm. Even the background ache in his off hand was gone. He was astounded - the turncoat medic was certainly more competent than he appeared.

“Thank you.” His hand felt better, but he knew from past experience with Ratchet’s maintenance that the relief was fleeting. Ultra Magnus didn’t want the soothing touch to leave yet.

“Don’t think that’s fixed it. All of this --” Knockout’s slender digits trailed from Ultra Magnus’s shoulder down to his hand, “-- is just a symptom.” He tapped the back of the truck’s helm near the medical port.

“I wouldn’t know how to...that is, do you have a suggestion?”

“I do, actually. With your type, you need to be in control all the time,” Fingertips made hard circles between his shoulders, “but you can’t make yourself give that up.” Claw tips stroked along his massive pauldrons and down his upper arms, then back up to his neck.

“I’ve found that in order to relax, sometimes you have to give up that control. Not yourself, that doesn’t work - but to someone _else_.” The heady purr of a high performance engine rang in his audials as the former Decepticon’s exvents rushed past his cheek.

“Are you suggesting yourself?”

“Naturally.” The vain mech’s confidence paired with obvious skill was intriguing.

“What would this involve?”

“Maintenance...mostly.” He could hear the quirked up smile in the other’s voice, and whatever the medic was offering, he wanted more.

“If I am correct in assuming what you are offering, perhaps it is best if we relocated.”

“Now that’s what I wanted to hear.” Knockout tapped his shoulder twice, and stepped away. Ultra Magnus hadn’t realized he’d been held there by the other mech’s words and his own want until the sports car released him. Processor in a daze from the unexpected pleasure and the realization that yes, this is exactly what he needed, he stood to walk a bit too close behind the medic. From this position he was well able to take a completely unprofessional look at his newest teammate. Deep red finish gleamed over casually sensual curves, strong grey lines showed raw power barely restrained beneath the surface.

Knockout turned on a heel to face Ultra Magnus outside the taller mech’s door, weight to one pede. Ultra Magnus realized he was staring, but remembered that now, he _could_.

“After you.” Knockout waited for him to unlock the door and followed him inside. Ultra Magnus heard the whoosh of the door closing and there was an explosion of EM radiation behind him. He turned to see Knockout’s expression with no pretense, nothing hidden.

Ultra Magnus was going to get thoroughly dominated by an ex-Decepticon and _love_ it.

Gorgeous engineering stalked forward, optics locked on his, and Ultra Magnus found himself backed up against his berth. A hand, promising pleasure and pain, pulled down on his hip fairing and he was forced to sit heavily on the edge.

He looked up. Crimson optics narrowed slightly, lip plating pulled up on one side into a self-satisfied smirk.

“I did not say you could look at me.”

Ultra Magnus jerked in surprise, still maintaining optic contact. “I…”

“Those who break the rules --” Knockout’s hand moved from his hip down his leg, “deserve _punishment._ ” Sharpened claws tightened around behind his knee joint, then scored his paint up the inside of his thigh. He invented sharply, but kept his optics on the other mech’s faceplates.

“No? Maybe you need a bit more _encouragement_ to not break the rules, then.” Ultra Magnus didn’t know what to expect. “So, you’re used to dealing with justice, what do you think would be appropriate, hm?”

Whatever Ultra Magnus had been bracing himself for, this wasn’t it. “I...um, I don’t believe I have any precedents to go upon…”

“Unfortunate. Be creative. Surely there’s _something_ that you have thought of, tucked somewhere in the depths of your processor,” his helm was caressed, “that you’ve _never_ told anyone about.”

Ultra Magnus searched his processor, undoing locks of rules and regimentation, scouring memories. What was the correct course of action in this instance was the opposite of the regulations for how he ran his life usually. “Perhaps…” his fans juddered, his vocalizer locked up with the embarrassment.

“Go on.”

“Perhaps corporal punishment is in order.”

“Don’t hide. I know you have a _specific_ one in mind.”

“Ah…” he couldn’t say it, that was never something he could admit to, but here...here he could. Here, his interface systems pinged him insistently demanding more of whatever was going on in his central processor. “Spanking,” he whispered.

“ _Good_. Now, that wasn’t so hard, was it?”

Ultra Magnus didn’t respond, the relief at having finally spoken it aloud to someone who understood still keeping him enthralled.

“ _Wasn’t it?_ ” the medic hissed.

“Yes.” Ultra Magnus said, with more conviction this time, but wonder still in his voice.

“Stand up.” Ultra Magnus stood, compelled to follow Knockout’s voice.

The smaller mech pointed at the floor. “Hands and knees.” Ultra Magnus hesitated for a moment, usual decorum warring with new protocols.

“Now.” Ultra Magnus lowered one knee, then the other, before tilting forward and resting his weight between hands and knees. He felt the weight of a hand on his backstruts move slowly back and forth.

“Every time I spank you,” Ultra Magnus couldn’t suppress the sudden gear slip, “you will count the number.” He could tell Knockout was waiting for a response from him.

“Yes.” Suddenly his pain receptors were firing, filling his HUD with urgent warnings.

“Yes... _sir_ ,” the red mech drawled.

“Yes sir.” Knockout’s hand struck his aft again, hitting the other side.

“I think you forgot something.” Amusement colored the other mech’s field.

“Two...sir.”

“Much better.” A slap landed, stinging his dermal receptors.

“Three, sir.” Another one, higher up this time.

“Four, sir.” Knockout’s hand caressed his aft, the sections that he’d hit feeling abnormally warm as self-repair started up and energon was rerouted to the area. The hand landed again, sharp and he moaned, forgetting to muffle himself as he usually did.

“Five, sir.” This situation was absolutely absurd. Here he was, in a ridiculous position being _spanked_ by a much smaller mech who had been his enemy, and he was the most relaxed he’d felt in - a very long time. It did not hurt that his interface system was very much on and the wires crossed in his processor such that after the shock of pain, pleasure raced through his lines, down his struts.

“Six, sir.”

“Seven, sir.”

“Eight, sir.” The only sounds he could hear was the pounding coolant under his heated plating, the throbbing of the sports car’s engine pitched higher than his own. And the clanking thud of a hand striking his aft.

“Ten, sir.” Knockout upped the pace, varying the timing so he couldn’t learn the pattern.

“Seventeen, sir.” He sucked air into his vents. All he had to do was count.

“Thirty, sir.” The light touches sent shivers up his backstruts, his plating oversensitive.

“Thir...ahh!” The unexpected slap caught him off guard. “Thirty-one, sir.”

“Really?” More slaps rained on his aft in quick succession.

“Th-thirty-six, sir.” He couldn’t tell if he wanted to press closer or arch away from the teasing claw tips at the seams in his thighs.

“I think you may have miscounted.”

“Thirty-seven, sir?”

“Wrong.” A few hard blows that he felt deep beneath his plating fell.

“Forty-two, sir!” His voice wavered even as he cried out. There was only his frame’s demands for more even as he felt he couldn’t bear it. That wasn’t his choice to make. He drew in a ventilation and blew it out, all his mind focused on when the next blow would fall.

He waited.

He tensed up in anticipation of the pain.

It didn’t come.

He let out the vent he’d been holding in.

Knockout’s hand connected with Ultra Magnus’s aft.

“Ah!” He yelled. Primus that had _hurt_. He prepared himself for another.

“Forgetting something?” Oh no. He hadn’t counted. He didn’t remember.

“Forty-two, sir?”

“Nope.” A single claw tip ran down his back, along his hip, before Knockout’s whole hand grabbed his hip and yanked him backwards, destabilizing his position.

“Forty-four, sir?”

“Incorrect,” Knockout continued distracting him. He ran his hand up Ultra Magnus’s thigh and groped his aft, the pressure causing all the overtaxed sensors to flare up with a different sensation.

“Forty-three, sir?”

“There you go.” Ultra Magnus held himself still, trying not to writhe into the hand that was so fragging close to where he wanted it. He panted, air cooling struggling to keep his engine temperature low. Soft touches turned into a firm grope on his aft, and he arched his back into Knockout’s hand, seeking more.

Headlights pressed up against his back, the vibrations of Knockout’s engine shook his frame and he felt his clutch depress and he released into a lower gear. Meanwhile, his interface systems keyed up further in a rush of rerouted coolant and increased energon demands.

“You’ve been good,” the hand was gentle over his dented plating, “So I think you deserve a reward. Get on the berth.”

Ultra Magnus didn’t need to be told twice, he just stood, somewhat unsteadily but Knockout guided him up, hand firmly on his forearm. He didn’t know what position to assume so he stalled standing before the berth. Knockout expertly used Ultra Magnus’s greater height and weight against him and he fell backwards onto the berth, knees bent over the side.

Ultra Magnus opened his eyes to a smirk. He did not know what that particular expression meant yet, but he guessed that Knockout knew what was coming next. He did not know what to do, wanting more, wanting whatever Knockout wanted, wanting to not know what would happen.

He felt a pede between his own. “Keep these apart. I shouldn’t have to tell you again.” Ultra Magnus spread his legs, suddenly feeling very exposed but at the same time wanting to be stripped further beneath the scrutiny of impassioned red optics. Hands ran up over his thighs to flatten out over his abdomen, trace up his chest plating and Ultra Magnus felt his valve clench, his spike straining against the panel between his opened legs. Knockout’s hand stroked over the glass of his chest and he gasped when he suddenly felt a wet lick at one of the alt mode lights on his torso. A claw tip swiped up along the glowing biolight on the side of his waist, before he felt the sports car’s lip plates close around the exposed wiring under his chest plating.

He shouldn’t be doing this. What was he doing, he was breaking _every_ rule in the datapad --

\-- one clawtip drew lines over his chest plating --

\-- he shouldn’t be here, he was _fraternizing_ with someone who had recently been a prisoner of war, there were so many things on his list…

A harsh slap shook his processor and stung his cheek plating.

“I know what you’re thinking. _Don’t_.” Hands wrapped around the top of his hips and tightened. “You have much, _much_ better things to be doing right now. Such as _this_.” Knockout pulled himself into Ultra Magnus, rolling his hips and shamelessly grinding their interface panels together.

Ultra Magnus couldn’t help but moan, “ _Please_ …”

Knockout smacked him on the thigh. “Please... _sir_.”

“Please, sir.”

“I have absolutely _no_ idea what you’re asking me for,” Knockout drawled, even as he undulated his hips slowly.

“Please, please _frag me, sir!_ ” All decorum disappeared. He _needed_ this, he needed _him_ …

Knockout nipped underneath his chestplates and followed with more attention to his alt mode lights, before he licked a wide, wet swath down Ultra Magnus’s abdomen. Dentae closed around the strip of glowing blue light at the top of his thigh, energon flowing just below the surface with the rhythmic pulses of his fuel pump.

He liked where this was going.

Knockout was teasing the gap between the plating of his thigh and his interface panel. He squirmed, trying to force contact where he wanted it.

Then there was none.

Ultra Magnus opened his optics to see Knockout’s lip plates glossy with oral fluid, his optics intense and hooded, before the beautiful red mech bent down to kiss down his abdomen, down his hip plating, down his panel and _sucked_.

He opened, paneling folding out of the way and his spike rushed to pressurize fully. His valve was undoubtedly a glistening mess as he tilted his hips in an obscene offering. He didn’t care how he looked, he only wanted to feel.

Feel Knockout’s hands on his frame, glossa between his seams, lip plating on his _oh!_

A hand pressed down on his hip, preventing him from bucking as Knockout’s glossa teased the tip of his spike before sinking down to fully engulf him. He tensed helplessly, holding his ventilation still as his fans stalled out. The wet intake around him slid up, then Knockout sucked, glossa forming a tight seal over the tip. He let go, airbrakes releasing, as the medic’s helm began bobbing shallowly. He kept himself quiet out of habit, but the glare of knowing red optics forced him to undo his self-imposed restriction and he let out a staticky exvent. Knockout took him to the base again and did he knew not what. He moaned, deep tones flooding his frame and transferring to the other mech’s. The medic hummed appreciatively, the vibrations of his vocalizer transferring to Ultra Magnus’s spike.

Knockout’s glossa flicked up the sensitive underside of Ultra Magnus’s spike and somehow flattened out at the tip before the medic sucked the head inside again. He drew Ultra Magnus in with impossible amounts of suction and released with the soft lining of his intake rubbing along the shaft, up and down, down further, Knockout’s chevron to Ultra Magnus’s pelvic plating.

And he swallowed.

The closure and inward motion of Knockout’s intake mechanisms pulled on Ultra Magnus’s spike and his fingers ground into his palms as he desperately restrained himself from thrusting up into perfection.

Ultra Magnus groaned with wanton desire for more, anything Knockout would give him. His engine growled, revving repeatedly, desperate to throw into a gear and go.

Just when he believed he could hold himself back no longer, Knockout licked up his entire length and caught his optics.

“Well?”

“Please, sir, please,” Ultra Magnus didn’t beg, but here, he had to. “Sir, I _need_ …”

Knockout’s glossa traced a lazy circle around the head of his spike.

“...I need _you_.”

“You need me? _Really_ , now. I’m quite,” small digits wrapped around the base of his spike, “here.”

“Please!”

“Please _what?_ ”

“Please sir _frag me!_ ”

“That’s more like it.” Knockout climbed up, sinfully proportioned legs settling around him. He leaned forward, hot exvents on Ultra Magnus’s neck as he bit down on cabling. Ultra Magnus’s ventilation hitched and his backstruts arched, pushing his hips up to rub his spike up against Knockout’s open interface array. Charge zipped through lubricant, urging the sports car to rock back and forth slowly, building up capacitance, smearing conducive fluid over a wider area. Knockout accelerated the pace, hips snapping forward as he pressed his external valve nodes to the underside of Ultra Magnus’s shaft, his own spike trapped between their abdomens and dripping lubricant. Ultra Magnus heard Knockout moan through a bitten lower lip, saw his optics shuttered in unabashed bliss.

He was absolutely beautiful.

Ultra Magnus couldn’t help but buck up against Knockout, when suddenly the other mech’s hips jerked erratically and current surged between them. Knockout cried out through his overload, V12 shrieking as it was pushed to its limits, his entire frame tensed. Then his shoulders slumped as he panted, optics unfocused. Ultra Magnus’s spike throbbed, coolant pounding through his lines and he thrusted involuntarily up against Knockout’s slicked interface array as his arms came up to wrap lightly around Knockout’s waist.

Nothing mattered but what was in front of him right now. There was only plating pressed so close he couldn’t tell where his field ended and the fuzzy waves of pleasure emanating from the other mech began. Ultra Magnus didn’t know if it was allowed but he _wanted_ it so badly as he pulled insistently on Knockout’s hips, all but picking him up. Knockout’s knees settled below his shoulders as Ultra Magnus held him aloft, not noticing the compensations he made for his prosthetic hand, only seeing comprehension flicker in Knockout’s brightening optics.

Ultra Magnus looked up at Knockout’s face as thighs spread further around him.

“Lick,” Knockout ordered.

Ultra Magnus pulled Knockout down and swiped his tongue up Knockout’s valve, tasting lubricant before sucking on the same external node that Knockout had rubbed along the ridges of Ultra Magnus’s shaft earlier. He felt a hand at his helm, playing with his audial finials, stroking up the sides and pinching lightly at the tips. But soon Knockout wasn’t able to concentrate any longer as Ultra Magnus licked up the base of Knockout’s shaft and tilted Knockout’s hips while angling his head to suck on the head of Knockout’s spike.

Ultra Magnus didn’t care that this was perhaps the least dignified thing he had ever done - it just felt too slagging _good_ not to. He wanted to do this, and Knockout’s orders pushed him past the doubts and regulations that had no place here. He pulled Knockout into his intake, still firmly gripping the curve of those gorgeous hips, adjusting the depth and pace as he tried to imitate what Knockout’s glossa had accomplished on him.

Eventually he tired, the awkward angle and his lack of practice overtaking how much he was enjoying the sight of Knockout writhing above him, claws at his own headlights. He let Knockout’s spike slip out of his intake, and kissed down to lick at Knockout’s valve again. Ultra Magnus licked insistently at the folds, glossa flicking intently over that external node. His hands dug into Knockout’s smooth plating as he penetrated Knockout’s valve with his glossa, feeling the outermost calipers clench down around his glossa. He knew his faceplates were an embarrassing mess but he did not care, not when Knockout’s claws tightened around the side of his helm and he heard a faint keen. If Knockout was close to another overload, Ultra Magnus wanted to bring him there, and he sucked on Knockout’s node while flicking his glossa over it, and brought his good hand up to feel the slicked folds above his face.

Ultra Magnus slowly inserted a digit, up into Knockout’s slick valve and he felt Knockout clench around him hard. Refocusing on slowly licking over Knockout’s external node and partway up the base of his spike, Ultra Magnus stroked the outside of Knockout’s valve with his digit, before attempting to insert it again. This time, it slid in, Knockout moaning as Ultra Magnus’s digit pressed against sensitive valve lining. Ultra Magnus pumped his digit a few times before withdrawing and pressing the tips of two digits in, Knockout’s valve gripping around them as Ultra Magnus reached up into his partner. Ultra Magnus curled his digits inward on the downstroke, pressing up against a sensor cluster that had Knockout panting and grinding down on him.

“Please,” Ultra Magnus whispered, lip plating brushing against Knockout’s interface array. “Please, sir, I need you to frag me.”

“I already...am,” Knockout said, self-satisfaction evident in every line of his frame.

“ _Please_ , sir.”

Knockout just looked at him and tightened his calipers down on Ultra Magnus’s digits, deep in his valve.

“I will do anything, please, sir, I need…”

“ _Any_ thing?”

“Yes.” Ultra Magnus pleaded. “Yes, sir.”

Knockout’s weight abruptly left his faceplates as the sports car lifted himself up, unfolding to lay atop of Ultra Magnus, before blue optics flew open in shock before shuttering in satisfaction.

Knockout, the former Decepticon medic, was kissing him desperately.

It didn’t matter that whatever they’d started was unorthodox in the extreme. Ultra Magnus did not even know how to classify this, to even begin to count the numbers of ways in which all of this was wrong.

Maybe the rule books were wrong.

Perhaps the rules did not apply to every situation. Suppose he really did need a break from --

\-- mountains of forms, reports dating back an orn or more that he still hadn’t completed, legal research for Optimus Prime --

\-- Claws grasped blindly for the rim of sensors around the medical port in the back of his neck, before Knockout’s talented mouth sucked on a main line in his neck --

\-- not to mention learning to navigate the human “insurance” systems, which had to be the most alien concept he had run across during his entire stay on Earth --

\-- and his battle computers leaped on, screaming at him to evade the Decepticon.

“Don’t.” The voice above him dripped with promised menace. The soldier remembered he was powerless and the fear melted into heightened anticipation.

Ultra Magnus stared up in astonishment.

“Keep them off.” Claws tightened around his face. “There is nothing you can do except _feel_.”

Ultra Magnus shuttered his optics, sinking into the feeling of submitting to this dangerous mech, his every movement, thought and feeling controlled by the head-turner above him.

Knockout sat up a bit, reaching between his own legs to fondle between Ultra Magnus’s, digits wrapping around Ultra Magnus’s spike, slowly pumping. Ultra Magnus didn’t know what to expect next, not wanting the attention to his spike to stop, his lack of visual input forcing him to focus on Knockout’s touch.

Was he using his mouth again? No, his thighs were in the wrong… “Ohhh!” he groaned as Knockout guided Ultra Magnus’s spike into himself. He could hear Knockout’s impatient hiss as he waited for his outermost valve calipers to adjust. He wanted more, he wanted Knockout to surround him, take him completely.

Knockout lifted and dropped his hips shallowly, gradually bringing more of Ultra Magnus inside him, his engine revving in time, racer’s processor wanting to floor it already. Ultra Magnus resisted the impulse to pull Knockout down onto himself, watching him rise and fall, before finally, Knockout fully enveloped him. Making small rocking motions, Knockout ground his hips in circles atop Ultra Magnus. He could feel the calipers tense around him, before relaxing once again. Knockout rocked forward once, twice, the low strut vibrating promise of first gear revving up into drop into second. Knockout raised up further this time, before seating himself again. With every bounce, the distance he traveled increased, longer strokes up and down Ultra Magnus’s shaft, paced in time with Knockout’s twelve cylinders.

Knockout slowed, as if to corner a turn, then accelerated steadily, pistoning up and down. The view, from Ultra Magnus’s perspective, was amazing. Perhaps he wasn’t supposed to look but he had to see what had him feeling so utterly _taken_.

Optics met. Ultra Magnus tensed, for punishment. He saw the glimmer in Knockout’s optics, as he leaned forward and held him in a stare. Knockout licked his lip plating as he ground their interface arrays together, and gripped Ultra Magnus’s forearms, pinning him to the berth.

Knockout sat up, raising up almost all the way off Ultra Magnus’s spike before falling, their plating clanking with every meeting. Ultra Magnus’s charge was building steadily, and he could not keep himself still any longer, drew his knees up to get leverage for his pedes and thrust up into Knockout as he crashed down. Knockout squealed like tires on pavement, burnt rubber and petrichor on a freshly watered track, lubricant drenching his thighs as the hydraulics bounced him up and down like a lowrider. Knockout gasped for air, intercooler failing, scoops ramming more air through his overheating frame. Ultra Magnus let his truck engine power him up into Knockout, the much lighter sports car carried aloft by the force of his thrusts, gravity pulling him back down around Ultra Magnus, bottoming out after bouncing over a bump in the road. Suspension tuned for the racetrack, not long potholed roads, squeaked and Knockout moaned constant encouragement.

“Oh, oh frag yes, _good_ _bot_.” Ultra Magnus could see the glassy, overcharged look in Knockout’s optics he remembered from earlier and hit the accelerator.

“Ah, haah, _harderrr!_ ” Knockout demanded, and Ultra Magnus floored it.

Knockout screamed, valve calipers clenching erratically as the ridges of Ultra Magnus’s spike tripped sensors faster than he could process. And he kept screaming, through another overload, as he went impossibly tight around Ultra Magnus’s spike, discharging current straight to his nodes at high amplitude.

“ _Please!_ ” Ultra Magnus groaned, it was too much, he couldn’t hold back anymore.

“Yes, yes, oh frag yes, keep--aah!”

Ultra Magnus pulled Knockout’s hips down onto his, steadied the exhausted grand tourer as he snapped up, staying the course. Can’t turn on ice, just gun it and hope to keep your tires gripping. He tried, chasing his overload, but couldn’t quite trip his breakers. Something was missing. Ultra Magnus’s hips fell back to the berth, his hydraulics worn out, stays aching even as he desperately wished to keep going.

Ultra Magnus looked to his partner, who had that cocky smirk back. Knockout had recovered and was raring to race another heat. Rocking forward, rolling back, Knockout undulated his hips, teasing.

“What, can’t keep up with me?” Knockout dared. Ultra Magnus could not refuse that challenge.

Claws tightened around his chest plating before bracing Knockout’s weight as the sports car slowly rolled into Ultra Magnus’s thrusts. He could feel it, charge coiling up in his capacitors, as he panted with the effort. He just let Knockout be the pace car, following his lead.

The amount of control Knockout wielded over him caught in his vents, as he watched the fluid movements of the racer above him. Lightweight plating pulled taut over a narrow waist as he gyrated, vents dumping excess heat that shimmered in the air. Ultra Magnus let his optics shutter, moving with the incredible ride above him. He didn’t notice that his pants for air to cool his systems had bled into his vocalizer, exvents rushing by colored with the deep tones of his voice.

Nothing mattered now but _feel_.

The feel of lithe, precise movements above him, thighs pistoning, the surges of electricity circuiting between them, the ethereal weight of lust prickling at his EM sensors. He drowned in sensation, ruthlessly denying any processing power to stray thoughts.

“Look at me.”

Ultra Magnus’s optics snapped open, focusing immediately on Knockout’s faceplates.

“Overload for me, now.”

All of his breakers tripped at once, current surging through his systems, every node on his spike connected with the flow of electrons to and from Knockout’s valve, his own clenching in time with the unending spurts of transfluid. Ultra Magnus yelled, all the force of that depth keening up high into spark-deep cries. His backstruts arched, his weight held up on only heels and helm as he lost all control of his frame.

The initial rush over, he sank into the berth, unable to do anything but quietly moan with the continued pulsations of his interface array, Knockout’s valve still cycling down around him. Knockout leaned forward to lie atop Ultra Magnus, and the direct contact between plating was comforting, as their EM fields fully meshed, fuel pump timing falling into synchronization.

After a time, Knockout pulled himself off of Ultra Magnus and proceeded to make himself comfortable on Ultra Magnus’s berth. Ultra Magnus looked at him, a little confused and nervous, unsure of what to do since he had nothing to go on, as this situation was still too new. Knockout must have caught the mild distress in Ultra Magnus’s field and seen his furrowed brows because he looked up, then motioned.

“Come here.”

Ultra Magnus went. Knockout deftly poked Ultra Magnus into the position he wanted him in, then curled up with his shoulder wheels to Ultra Magnus’s chest. Pulling Ultra Magnus’s arm over his shoulders, Knockout then slowly stroked his digits over Ultra Magnus’s own. He didn’t know which arm it was. It didn’t matter. The contentment radiating from Knockout’s cooling frame and the purrs of his idling engine were irresistible, and Ultra Magnus drifted into recharge.

He awoke to strut deep satisfaction and a plethora of HUD alerts all pinging him for attention. The awareness of a not unpleasant ache in his aft plating reached his slowly booting processor. That was most assuredly out of the ordinary, what could have...his optics flickered on. Red plating stretched for curvy miles, languorously stretched out on his berth. All the data from their previous activities flooded his central processor. Right, that.

Ultra Magnus was so thoroughly fragged. He reviewed his memory logs and winced. The volume was undoubtedly loud enough to travel not only beyond the door but halfway through the base. Given the duty roster and groundbridge logs - and accounting for the speed of gossip - there was absolutely no way that everyone did not know _exactly_ what had happened already. Ultra Magnus’s optics refocused on a flash of movement as Knockout stretched, then propped his torso up on one elbow to look at him.

“Relax, it’s not like anyone would be paying attention here when they're all off fragging each other anyway. Besides, from what I could hear? Some _lucky_ bot actually managed to get under the Prime's hood."

“What...how did you. _Prime?_ ” Of all the strange things Ultra Magnus had ever heard --

“I just came down the hallway and ohh,” Knockout’s engine rumbled deeply as his voice dipped into a sultry growl, “there is absolutely _no_ mistaking **that** voice.”

Ultra Magnus blinked and reset his audial drivers. “Who?”

Knockout smirked. “I’m not _entirely_ sure. I think you’ll find out soon enough.”

It appeared that Ultra Magnus was not the only bot on base to have, ah, engaged in off-duty activities.

“Turn over.”

Ultra Magnus hesitated for a second.

“I am a medic, remember?”

Chestplates to the berth, Ultra Magnus rested his helm on his forearm plating. Knockout’s touch to his backstruts was more comforting than strictly professional. Hands that had brought spark deep pleasure through the pain he had wanted so much to experience checked over his aft. Ultra Magnus turned his helm and watched the intent expression on Knockout’s faceplates as the specialized sensors in his digits fed detailed information to his processor.

“Self-repair’s functioning normally, my aim is impeccable, sitting down will be mildly uncomfortable but only for a short while, and I quite hope you had as much fun as I did,” Knockout rattled off in the affectedly nonchalant manner that Ultra Magnus was learning was a defense mechanism against worry. He’d seen it especially in those tense early meetings where Knockout tried not to let it show how desperate he was to prove himself reliable. Nervous tension leaked through Knockout’s barely controlled EM field.

“I did.” Ultra Magnus raised himself up on his elbows. “I most assuredly did.”

“Really?” Knockout’s shocked, unguarded happiness at Ultra Magnus’s answer was evident in every line of his plating. “I ah, of course. My pleasure.” The sports car couldn’t hide his embarrassment.

Ultra Magnus could feel a warm smile spread across his faceplates as his optics brightened.

“So,” Knockout’s optics brightened as he drawled. “Want to get regular tune-ups?”

Ultra Magnus nodded as he reached an arm out to press their plating together again.

 

 


End file.
